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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Christophe de Dinechin <dinechin@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Yan Zhao <yan.y.zhao@intel.com>, Jason Wang <jasowang@redhat.com>,
	Kevin Kevin <kevin.tian@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>
Subject: Re: [PATCH v3 00/21] KVM: Dirty ring interface
Date: Thu, 9 Jan 2020 17:21:01 -0500	[thread overview]
Message-ID: <20200109171909-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <feffe012-0407-128a-185a-42cb9d5aac5c@redhat.com>

On Thu, Jan 09, 2020 at 09:51:50PM +0100, Paolo Bonzini wrote:
> On 09/01/20 20:13, Michael S. Tsirkin wrote:
> > That's one of the reasons I called for using something
> > resembling vring_packed_desc.
> 
> In principle it could make sense to use the ring-wrap detection
> mechanism from vring_packed_desc instead of the producer/consumer
> indices.  However, the element address/length indirection is unnecessary.
> 
> Also, unlike virtio, KVM needs to know if there are N free entries (N is
> ~512) before running a guest.  I'm not sure if that is possible with
> ring-wrap counters, while it's trivial with producer/consumer indices.
> 
> Paolo

Yes it's easy: just check whether current entry + 500 has been consumed.
Unless scatter/father is used, but then the answer is simple - just
don't use it :)

-- 
MST


  reply	other threads:[~2020-01-09 22:21 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 14:57 [PATCH v3 00/21] KVM: Dirty ring interface Peter Xu
2020-01-09 14:57 ` [PATCH v3 01/21] vfio: introduce vfio_iova_rw to read/write a range of IOVAs Peter Xu
2020-01-09 14:57 ` [PATCH v3 02/21] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_iova_rw Peter Xu
2020-01-09 14:57 ` [PATCH v3 03/21] KVM: Remove kvm_read_guest_atomic() Peter Xu
2020-01-09 14:57 ` [PATCH v3 04/21] KVM: Add build-time error check on kvm_run size Peter Xu
2020-01-09 14:57 ` [PATCH v3 05/21] KVM: X86: Change parameter for fast_page_fault tracepoint Peter Xu
2020-01-09 14:57 ` [PATCH v3 06/21] KVM: X86: Don't take srcu lock in init_rmode_identity_map() Peter Xu
2020-01-09 14:57 ` [PATCH v3 07/21] KVM: Cache as_id in kvm_memory_slot Peter Xu
2020-01-09 14:57 ` [PATCH v3 08/21] KVM: X86: Drop x86_set_memory_region() Peter Xu
2020-01-09 14:57 ` [PATCH v3 09/21] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] Peter Xu
2020-01-19  9:01   ` Paolo Bonzini
2020-01-20  6:45     ` Peter Xu
2020-01-21 15:56   ` Sean Christopherson
2020-01-21 16:14     ` Paolo Bonzini
2020-01-28  5:50     ` Peter Xu
2020-01-28 18:24       ` Sean Christopherson
2020-01-31 15:08         ` Peter Xu
2020-01-31 19:33           ` Sean Christopherson
2020-01-31 20:28             ` Peter Xu
2020-01-31 20:36               ` Sean Christopherson
2020-01-31 20:55                 ` Peter Xu
2020-01-31 21:29                   ` Sean Christopherson
2020-01-31 22:16                     ` Peter Xu
2020-01-31 22:20                       ` Sean Christopherson
2020-01-09 14:57 ` [PATCH v3 10/21] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() Peter Xu
2020-01-09 14:57 ` [PATCH v3 11/21] KVM: Move running VCPU from ARM to common code Peter Xu
2020-01-09 14:57 ` [PATCH v3 12/21] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2020-01-09 16:29   ` Michael S. Tsirkin
2020-01-09 16:56     ` Alex Williamson
2020-01-09 19:21       ` Peter Xu
2020-01-09 19:36         ` Michael S. Tsirkin
2020-01-09 19:15     ` Peter Xu
2020-01-09 19:35       ` Michael S. Tsirkin
2020-01-09 20:19         ` Peter Xu
2020-01-09 22:18           ` Michael S. Tsirkin
2020-01-10 15:29             ` Peter Xu
2020-01-12  6:24               ` Michael S. Tsirkin
2020-01-14 20:01         ` Peter Xu
2020-01-15  6:50           ` Michael S. Tsirkin
2020-01-15 15:20             ` Peter Xu
2020-01-19  9:09       ` Paolo Bonzini
2020-01-19 10:12         ` Michael S. Tsirkin
2020-01-20  7:29           ` Peter Xu
2020-01-20  7:47             ` Michael S. Tsirkin
2020-01-21  8:29               ` Peter Xu
2020-01-21 10:25                 ` Paolo Bonzini
2020-01-21 10:24             ` Paolo Bonzini
2020-01-11  4:49   ` kbuild test robot
2020-01-11  4:49     ` kbuild test robot
2020-01-11 23:19   ` kbuild test robot
2020-01-11 23:19     ` kbuild test robot
2020-01-15  6:47   ` Michael S. Tsirkin
2020-01-15 15:27     ` Peter Xu
2020-01-16  8:38   ` Michael S. Tsirkin
2020-01-16 16:27     ` Peter Xu
2020-01-17  9:50       ` Michael S. Tsirkin
2020-01-20  6:48         ` Peter Xu
2020-01-09 14:57 ` [PATCH v3 13/21] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2020-01-09 14:57 ` [PATCH v3 14/21] KVM: Don't allocate dirty bitmap if dirty ring is enabled Peter Xu
2020-01-09 16:41   ` Peter Xu
2020-01-09 14:57 ` [PATCH v3 15/21] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2020-01-09 14:57 ` [PATCH v3 16/21] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2020-01-09 14:57 ` [PATCH v3 17/21] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2020-01-09 14:57 ` [PATCH v3 18/21] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2020-01-09 14:57 ` [PATCH v3 19/21] KVM: selftests: Add dirty ring buffer test Peter Xu
2020-01-09 14:57 ` [PATCH v3 20/21] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2020-01-09 14:57 ` [PATCH v3 21/21] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
2020-01-09 15:59 ` [PATCH v3 00/21] KVM: Dirty ring interface Michael S. Tsirkin
2020-01-09 16:17   ` Peter Xu
2020-01-09 16:40     ` Michael S. Tsirkin
2020-01-09 17:08       ` Peter Xu
2020-01-09 19:08         ` Michael S. Tsirkin
2020-01-09 19:39           ` Peter Xu
2020-01-09 20:42             ` Paolo Bonzini
2020-01-09 22:28             ` Michael S. Tsirkin
2020-01-10 15:10               ` Peter Xu
2020-01-09 16:47 ` Alex Williamson
2020-01-09 17:58   ` Peter Xu
2020-01-09 19:13     ` Michael S. Tsirkin
2020-01-09 19:23       ` Peter Xu
2020-01-09 19:37         ` Michael S. Tsirkin
2020-01-09 20:51       ` Paolo Bonzini
2020-01-09 22:21         ` Michael S. Tsirkin [this message]
2020-01-19  9:11 ` Paolo Bonzini

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